Changes (release for testing window rendering in GUI mode, win32 only)

• This is still only a test GUI window.
• Add support for glyph run alignment, rotation and flipping (using Unicode Variation Selectors VS4-VS14). See #571 for details.
• Update to Unicode 16.0 ("Large Type Pieces" support).
• Add support for GUI full screen mode.
• Add a GUI related config section:

  <config>
    <gui> <!-- GUI related settings. (win32 platform only for now) -->
        <antialiasing = off />   <!-- Antialiasing of rendered glyphs. Note: Multi-layered color glyphs such as emoji are always antialiased. -->
        <cellheight = 20 />      <!-- Text cell height in physical pixels. Note: The width of the text cell depends on the primary font (the first one in the font list). -->
        <gridsize = 0,0 />       <!-- Window initial grid size in text cells. -->
        <wincoor = 0,0 />        <!-- Window initial coordinates (top-left corner on the desktop in physical pixels). -->
        <winstate = undefined /> <!-- Window initial state: undefined | maximized | minimized -->
        <fontlist> <!-- Font fallback list (LF-delimited (\n), ordered). The rest of the fonts available in the system will be loaded dynamically. -->
            "Courier New\n" <!-- Primary font. Its metrics define the cell geometry. -->
            "Iosevka Term\n"
            "JetBrains Mono\n"
            "Cascadia Mono\n"
            "DejaVu Sans Mono\n"
            "Envy Code R\n"
            "Fira Code\n"
            "monofur for Powerline\n"
            "Lucida Console\n"
            "Consolas\n"
            "Anonymous Pro\n"
            "Source Code Pro\n"
            "NSimSun\n"
            "Noto Sans Devanagari\n"
        </fontlist>
        <testtext="test \e[41;94m UTF-8 \e[m string 👌︌︉︅󐀮😃👌︋︅󐀮 (See ~/.config/vtm/settings.xml: /config/gui/testtext/)"/>
    </gui>
  </config>

• https://learn.microsoft.com/en-us/cpp/overview/cpp-conformance-improvements?view=msvc-170#__va_opt__-is-enabled-as-an-extension-under-zcpreprocessor

Note: vtm automatically switches to the graphical mode if it is launched by the graphical shell (explorer.exe), or by the start vtm.exe command (e.g. on Windows Core).